(1) Field of the Invention
The present invention relates to a process and apparatus for removing contaminates from edible cooking oil. More particularly, the present invention relates to a process and apparatus for continuously withdrawing a continuous stream of hot edible cooking oil from a cooking bath, removing at least a portion of contaminates in the cooking oil and thereafter returning the cleaned cooking oil to the bath.
The present invention also relates to a process for cooking comestibles such as nuts in an edible oil bath and continuously maintaining the quality of oil in the bath during the cooking process by withdrawing a continuous stream of the oil, cleaning the oil and returning it to the bath.
(2) Description of the Prior Art
During the cooking of comestibles in oil, and in particular in the cooking of snack foods in oil, the cooking oil becomes contaminated with substances transferred from the comestibles being cooked into the hot oil.
In the processing of edible nuts which are conventionally packaged and sold as snack-type products, nuts such as peanuts, cashews, almonds, walnuts, filberts, macadamia nuts, pecans and the like are coated with sugars and/or adhesive solutions for adhering the sugars to the nut. These sugars may comprise sucrose, corn syrup, honey, fructose or any number of sugars used in the coating of nuts and are transferred to the oil bath during oil roasting of the coated nuts. In addition, an adhesive, particularly a carbohydrate adhesive, may be used to adhere the sugars to the coated nut during roasting, and gum may be transferred to the oil bath during or roasting of the nuts.
The coated nuts are roasted at process temperatures of between about 250.degree. and about 400.degree. F. During roasting the coating comprising sugar will become tacky and some of the coating will transfer to the oil. As the coating particles are maintained in the oil, they will begin to carbonize and/or carmelize, thus contaminating the cooking oil. In a short period of time the oil becomes unsuitable for cooking nuts because the taste and coloration of the nuts falls outside of desired process standards. More particularly, the carbonized or carmelized sugar coating may adhere to the tack coated nuts as they move through the oil and the taste of the nuts is adversely affected. Moreover, the oil bath darkens to a point where the nuts produced are darkened outside of desired process standards.
In addition, the process equipment can become fouled with the carbon and/or carmelized sugar coating transferred to the oil during the cooking process. Thus, as the oil degrades, the entire system and production line must be shut down to clean the nut roasting apparatus and remove the cooking oil and replace it with additional cooking oil. The additional cooking oil must be reheated to process temperatures before the process can be started. The down time for cleaning and replacement of the oil is a substantial factor in the cost of the product. The output of the equipment is reduced substantially by contamination of the oil and fouling of the equipment, thereby increasing the need for additional lines, which in turn requires substantial capital expenditure. Moreover, during the course of the process, as the cooking oil degrades, the quality of the product varies over the life of a particular oil bath. The quality of the product may be inconsistent due to oil degradation.
The temperature of the oil during processing is between about 250.degree. F. and 400.degree. F. and is difficult to clean during the continuous cooking of the comestibles in the oil bath. In a conventional oil bath, the oil is continuously circulated through a mesh filter which screens some of the larger particulate matter. In a case where nuts including a coating comprising sugars are processed, the screen can become clogged. Even if the screen is not clogged, the oil still degrades due to the fine nature of the sugars, which pass through the mesh filter.
It would be desirable to maintain oil quality thoughout the cooking process to thereby maintain a substantially uniform quality of the comestibles being cooked. It is also desirable to maintain the processing equipment in a clean condition. Through maintenance of the oil quality and maintenance of equipment in a clean condition, production can be increased or maximized by reducing process shutdown time. By reducing shutdown, the capacity of the equipment is increased, and the requirement for additional capital expenditures for additional equipment may, in some instances, be reduced or avoided.